Secretory cell (sc) in the midgut epithelium of P. angustus. A. Localization of secretory cell (sc) in the epithelium among basal regions of digestive cells (dc). Fragments of regenerative cells (rc), mitochondria (m), nuclei (n), electron dense granules (arrows), basal lamina (bl). Longitudinal section. TEM. Scale bar = 1.2 µm. B. A fragment of Fig. A with the electron dense granules (arrows). TEM. Scale bar = 0.3 µm.